US-A-2004/193122 describes examples of controlled discharge ostomy appliance including a seal that is urged against the exterior surface of a stoma. The stoma seal is carefully designed and supported so as to cooperate with the stoma tissue to form an occlusive, non-entrant seal. The seal obstructs discharge of liquid and/or solid body waste, while permitting flatus to escape along the interface between the seal and the stoma, and vent around the seal periphery to a dedicated flatus vent of the appliance. The appliance is removably attached to a body-side mounting wafer. A distensible waste collector is deployed when the appliance (with its seal) is removed from the body-side mounting wafer, to provide a closed collection space for body waste that may discharge spontaneously. The adhesive has a fixed size stomal aperture and an elastomeric seal extends peristomally between the adhesive and stoma, against which the stoma seal may also bear.
US-A-2004/006320 describes a different type of body-mounting wafer, normally for ostomy pouches, and including a stomal aperture that is manually moldable. Such a mounting wafer offers many advantages, especially ease of use and custom adaptation to each ostomate's unique size and shape of stoma. The adhesive wafer is flexible and includes exposed adhesive on both its skin-facing surface and its opposed non-skin-facing surface. The stomal aperture is manually moldable by rolling or folding back the rim of the adhesive wafer around the stomal aperture, into adhesive contact with its non-skin-facing surface. The adhesive contact anchors the adhesive wafer in its new shape around the stomal aperture. Despite the potential advantages, this type of moldable mounting wafer is generally incompatible with the aforementioned controlled discharge device. The presence of a rolled-back adhesive rim, with an exposed adhesive surface facing the seal, interferes with the carefully designed seal operation. In particular, the seal is vulnerable to adhering against the exposed adhesive surface of the wafer, either immediately on contact, or over time while the appliance is worn. The risk of adhesion can increase over time, because the moist environment at the stoma seal progressively softens the adhesive making it tackier. Adhesion of the seal to the rolled back adhesive rim in the wafer creates a closed system, which traps flatus at the stoma seal instead of permitting intended escape of flatus around the periphery of the seal. The pressure of trapped flatus may (i) weaken the seal allowing effluent to leak to the adhesive, (ii) weaken the adhesion of the wafer to the skin, (iii) risk the appliance separating unintentionally.
WO-A-2009/029610 describes a refined seal support for a controlled discharge device using resilient foam, and a fluid damper chamber, for controlling the seal force and position as the stoma changes dynamically while the appliance is worn. The seal combines flatus venting around the periphery of the seal, with ability for the seal to advance and retract adaptively to avoid prolonged application of excessive pressure on the stoma. However, the carefully designed operation of the seal would also be compromised if used with a moldable adhesive wafer of the type described in US-A-2004/006320 above. In addition to trapping flatus in the same manner as explained above, adhesion of the stoma seal to the exposed adhesive holds the seal captive to the adhesive wafer instead of the seal being able to advance and retract adaptively.
The present invention addresses at least some of the above issues.